She resigned from Labour in February 2019 alongside six other MPs in protest at Corbyn's leadership, and they formed the Independent Group, later Change UK.

In June 2019, she left Change UK to sit as an independent MP before joining the Liberal Democrats in September.

[9] After a period as opposition Whip, Smith was promoted to the front bench as the Shadow Deputy Leader of the House in October 2010.

[16] Smith is one of 71 MPs who have signed a petition to re-open the trans-Pennine route, and she has on more than one occasion headed debates in Westminster on the need for more railway investment in the north.

In July 2009, she introduced a symbolic Ten Minute Rule Bill to the House of Commons which, if accepted by government, would have changed the law to give people more legal protection against attacks by dogs.

Smith tweeted that her "first priority is always to do my job, to the best of my ability" and that her defeat was as a result of "a cabal of hard left members" who had "absorbed everyone's precious time and energy on an inaccurate and divisive motion of no confidence".

She defended her vote on the grounds that it would help member-constituent confidentiality and help prevent the private addresses of MPs being readily available to the public.

[24] The practice of MPs employing family members has been criticised by some sections of the media on the grounds that it promotes nepotism.

[28] These resignations were prompted by issues with Jeremy Corbyn's leadership of the Labour Party, including allegations of the mishandling of antisemitism and his approach to Brexit.

[30] In 2019, Smith attracted condemnation when, shortly after citing antisemitism as one of her reasons for leaving Labour at the Independent Group launch earlier that day, she appeared on BBC Two's Politics Live where she referred to fighting racism as "not just about being black or a funny tin..." before hesitating and then finishing the sentence with "from the BME community": the unfinished word was widely taken to have been 'tinge'.

[37][38] At the 2019 general election, she stood as a Liberal Democrat in Altrincham and Sale West, finishing in third place with 11% of the vote.

[39] During the election campaign, Smith complained that she was effectively being discriminated against because she would not receive the MP's LOOP (loss of office payment) as a consequence of changing constituencies if defeated – drawing an apparent contrast with controversial ex-Labour MP Jared O'Mara, who at the time had not ruled out defending his seat.